1. Field of the Invention
The invention relates to a burner for operation with gas and/or oil, including a central pilot burner system which can be operated with gas and/or oil as a diffusion burner or as a separate pre-mixing burner, optional additional means for feeding inert substances, and an annular main burner system surrounding the pilot burner system for pre-mixing operation with gas which can be admixed with the primary air flow from a multiplicity of nozzles.
2. Description of the Related Art
Burners of this kind and the applications and possible installations thereof are known from European Patent Application No. 0 193 838, corresponding to U.S. Pat. No. 4,701,124. This publication also describes the structure of such a burner in detail and is hereby expressly incorporated by reference, so that the ensuing description can be restricted to the novel details essential to the invention.
The burner known from the prior art is likewise suitable for operation with gas and/or oil, but it is not possible to perform both alternatives in pre-mixing operation. When a burner according to the prior art is to be operated with oil, the conventional structure operates as a diffusion burner, which has disadvantages in terms of the emissions of toxic substances. The prior art burner configuration has a multiplicity of nozzle tubes in the vicinity of the primary air flow and gas is admixed with the air flow in these nozzle tubes. In principle, this kind of admixture system can also be supplied with oil instead of gas, but in that case, because of the entirely different volumetric flows, the nozzles must be dimensioned quite differently. Hence once a system has been installed, it is only suitable for premixing operation with gas or with oil. Furthermore, the feeding point that is favorable for gas and is located upstream of the swirl vanes, is not particularly well suited for feeding oil and atomizing it finely, because the flow velocity of the air is relatively low in that region.